Le Petit Criminel (The Little Gangster) (1990)

Marc, a troubled teenager, is bored in his native, depressing city of Sete. One day, a simple phone call makes him aware of the existence of Stephanie, a sister he has never met. Armed with a pistol his mother found, he goes out to find her. He steals money from a perfume shop, and is then stopped by a policeman who wants to search him. In the car, Marc threatens the policeman with his gun, demanding that he helps him find his sister...